In combination with (motor-driven) transportation such as railroad, automobile or aircraft or in combination with ships, folding bicycles or scooters are used as muscle- or electrically driven vehicles. These vehicles intend to minimize time for commuting distances. Further folding bicycles are used for travels where there is not enough space for a 26/28-inch bicycle. To meet these objectives, the targets are smallest possible folding size, lowest possible weight and comfortable riding for a vehicle suitable for adults.
Regarding this, known commercially-available folding bicycles exhibit the following disadvantages:
a. They are relatively heavy (>10 kg), lighter versions are expensive because of more expensive lighter materials (for example carbon instead of aluminum).
b. The frame construction requires the use of many special components only manufactured for the respective bicycle frame, making it very expensive.
c. To achieve the targeted folding size, components such as brakes and shifting elements have to be manufactured individually for the respective folding bicycle.
d. Axially seen between the bicycle frame and the rear wheel the output sprocket of the chain transmission is arranged. This arrangement requires a minimum width of the rear-wheel-axle or, due to required chainstay lengths a long folding size in the folded state of the bicycle.e. Transmissions (planetary gears and derailleurs) are used with transmission ratios designed for large wheels. Consequently the driving sprocket must exhibit more teeth compared to large-wheel-bicycles, hence the cyclist makes the same distance with the same pedaling frequency as with large-wheel-bicycles. To achieve a suitable development of 7.5 m in the highest gear, these transmissions are suitable even with a large driving sprocket only for wheels starting from 20 inch, however at least 16 inch.
Conventional scooters exhibit the following disadvantages:
a. The energy expend is considerably higher than in the case of a bicycle.
b. The achievable speed with a scooter is considerably lower than with a bicycle.
When wheels smaller than 16 inch or 20 inch are used, further aspects relating to the cycling characteristics have to be taken into account for assessing the prior art:
Small front wheels react more quickly to steering movements and tend to jiggle even at lower speeds and on slightly uneven road surfaces.
When cycling over obstacles (objects, holes, elevations on the roadway) with small wheels, the steering motion can be severely impaired.
Bicycles having small wheels can exhibit shorter distances between the rear-wheel axle and the bottom bracket than bicycles having large wheels. Seen in the traveling direction, the further to the rear the center of gravity of the cyclist is situated, the greater is the risk that the front wheel lifts off when the cyclist accelerates.
Due to the gyroscopic effect that is considerably reduced in the case of small wheels, the cyclist's inertia has a larger influence affecting the cycling stability. If for example the cyclist in quick alternation steers to the one and to the other direction with a small front wheel, the mass of the cyclist produces a moment of inertia that trails the steering motion. This affects the control of a bicycle having small wheels. The cyclist's moment of inertia delays the cyclist's curve motion at the beginning of the steering motion and accelerates the cyclist's curve motion at the end of the steering motion. The frequency of the changes staying constant (for example during a slalom race), this effect builds up to the point that the bicycle starts to spin. Seen in the travel direction, the further to the front the center of gravity of the cyclist is situated, the greater are the destabilizing tilting moments from the cyclist's moment of inertia while cycling a curve.
Due to the considerably reduced gyroscopic effect cycling while standing up is in principle more unstable with smaller wheels than with large wheels.
Small wheels require more revolutions to achieve the same convenience for the bicycle as with bicycles having larger wheels.
The braking behavior is also essential for the cycling characteristics. For supporting his own moment of inertia on the handlebar while decelerating the sitting position usually forces the cyclist's arms to describe a straight line between the handlebar and the shoulder. Particularly compact-designed bicycles doesn't allow the arms to describe a sufficiently straight line, so that the cyclist can no longer brace his accelerated mass against the handlebar on greater deceleration from higher speeds and would fall toward the front over the handlebar or at least carries out a motion relative to the bicycle toward the front that affects the cycling stability.
Therefore the following points are essential to evaluate the prior art of bicycles having small wheels:
the cycling characteristics and the cycling stability
the folding size achieved
the development that are achieved for bicycles having small wheels
the braking behavior
It is a disadvantage of the following bicycles with small wheels that in case of quick steering motions the cycling stability is compromised by the above-mentioned tilting moments due to the construction, that puts the cyclist far in front. The specifications listed below as examples, describe bicycles having small wheels that, due to their construction, exhibit, seen horizontally, a large distance of more than 25 cm between the cyclist's center of gravity and the rear-wheel axle, the design-related causes being indicated in brackets:
DE 201 10 016 U1, DE 201 20 092 U1, U.S. Pat. No. 6,439,590 B1 (drive system having upstanding steps), U.S. Pat. No. 7,784,808 B2, U.S. Pat. No. 6,799,771 B2 (drive system having a two-chain transmission),
the bicycle dreamslide by dreamslide, S.A, Bures-sur-Yvette, France (bottom-bracket linkage and 16-inch rear wheel used because of the single-speed chain drive),
the bicycle microslider by dreamslide, S.A, Bures-sur-Yvette, France (two-chain transmission),
U.S. Pat. No. 5,186,482 A (two-chain transmission),
the bicycle Birdy Frog by Riese and Müller up to 2006 (rotatable fork dampened relative to the seat tube on the bottom bracket for fork-like suspension of the rear wheel),
U.S. Pat. No. 3,979,136 A (spur gear on the bottom bracket arranged in the direction of the rear wheel),
EP 1 995 165 A2 (drive system by means of foot plates, the center of gravity of the cyclist being in front of the bottom-bracket axle seen in the direction of cycling),
US 2007/0,069,499 A1 (chain must be passed below the frame, in the folded state the rear wheel must remain arranged below the seat tube to comply with the folding size)
U.S. Pat. No. 4,598,923 A (folding principle).
The bicycles in DE 201 10 016 U1 and in DE 201 20 092 U1 exhibit the disadvantage that the upstanding steps are rotatably connected to the rear-wheel axle, the chainstay length being at least as large as the front center having the disadvantages relating to cycling stability described above.
In contrast, the bicycles mentioned below as examples having small wheels exhibit, seen horizontally, a relatively short distance between the cyclist's center of gravity and the rear-wheel axle: DE 198 03 462 A1, U.S. Pat. No. 7,306,249 B2, DE 32 25 340 A1, U.S. Pat. No. 3,990,717 A, DE 203 11 511 U1, US 2005/0,263,979 A1, WO 2010/054 500 A1, DE 201 12 963 U1, U.S. Pat. No. 6,595,536 B1, WO 2007/057 992 A1, U.S. Pat. No. 6,595,539 B1.
However, they have the disadvantage that they exhibit a saddle and are preferably used seated. While accelerating the bicycle, the cyclist absorbs his own inertia with his hands on the handlebar preventing falling off the bicycle. In the case of the above-mentioned bicycles due to the seat position the force acting on the pedals is applied in front of the cyclist's center of gravity and/or due to the arms pointing forward the pulling force acting on the handlebar is oriented toward the rear. The pulling force acting toward the rear on the handlebar and the force acting toward the rear on the saddle induced by the cyclist's moment of inertia when accelerating in combination with the cyclist's center of gravity, that, seen horizontally, is already arranged very close to the rear-wheel axle, lift the front wheel off the ground even at low pulling forces acting on the handlebar.
Other known bicycles don't allow the cyclist to brace his inertia against the handlebar in the case of a stronger breaking deceleration. Due to the handlebar position the cyclist has to ride with angled arms and cannot stretch them. On stronger deceleration, the cyclist would carry out a motion toward the front relative to the bicycle and fall toward the front, possibly over the handlebar. Examples for this are in: DE 32 25 340 A1, U.S. Pat. No. 7,306,249 B2, US 2003/0,114,274 A1 and U.S. Pat. No. 1,381,281 A.
The folding size and the weight of a folding bicycle are very important for everyday use. The prior art relating to the achievable folding size is described below:
Due to the design of many known folding principles for bicycles with small wheels, in the folding state both wheels being situated one behind the other but at least do not lie next to each other congruently. A disadvantage is, when using wheels with 12 inch and more, these folding principles result in a corresponding folding length of at least circa 65 cm. Examples for this are in EP 1 600 368 A2, WO 2010/054 500 A1, US 2007/0,069,499 A1, U.S. Pat. No. 7,306,249 B2, DE 203 11 511 U1, EP 0 388 540 A1, WO 2009/145 599 A2, WO 2006/111 590 A1, U.S. Pat. No. 4,824,130 A, DE 40 06 095 A1, U.S. Pat. No. 3,419,283 A, U.S. Pat. No. 6,196,566 B1, US 2005/0,230,933 A1, US 2007/0,024,023 A1, US 2003/0,051,934 A1.
A few bicycles are known comprising a top tube with two rotatably connected frame tubes, one is rotatably connected to the head tube and the top tube is rotatably connected centrally to a further frame part to which in turn the rear wheel and the bottom bracket are attached. The head tube connects a steering column to the front wheel. Due to the folding principle of these bicycles the two frame parts connected to the top tube can be folded together scissors-like. The disadvantage of these bicycles consists in that the longest side of the folding size is at least 65 cm and that the folding size L+W+H of the bicycle is at least 120 cm. However, by far the greater disadvantage is that such a small folding size is only achieved by using particularly small 6-inch or 7-inch wheels, which markedly reduces the ride comfort and the usability. Examples for this are in: US 2005/0,263,979 A1 and WO 2010/054 500 A1.
Folding principles for bicycles having small wheels often realize a folding-together of steering column and seat tube in the same sense, the seat tube and the steering column then approximately lying parallel to the longest side of the folding size. The disadvantage of these folding principles consists in that this longest size is at least 70 cm. Examples for this are in U.S. Pat. No. 4,844,494 A, U.S. Pat. No. 6,032,971 A, U.S. Pat. No. 6,595,536 B1, U.S. Pat. No. 7,055,842 B1, US 2005/0,230,933 A1, US 2003/0,114,274 A1, US 2007/0,024,023 A1, U.S. Pat. No. 6,883,817 B2, DE 603 03 842 T2, U.S. Pat. No. 6,695,334 B2, DE 203 11 511 U1, DE 198 03 462 A1, U.S. Pat. No. 6,799,771 B2, U.S. Pat. No. 7,290,780 B2, U.S. Pat. No. 4,718,688 A, U.S. Pat. No. 4,895,386 A, U.S. Pat. No. 3,979,136 A, U.S. Pat. No. 5,785,338 A.
Further known bicycles, too, exhibit a longest side having a length of at least 65 cm due to the folding principle. Examples for this are in: U.S. Pat. No. 6,032,971 A, U.S. Pat. No. 6,595,536 B1, US 2005/0,230,933 A1, US 2007/0,024,023 A1, U.S. Pat. No. 3,419,283 A, U.S. Pat. No. 4,132,428 A, U.S. Pat. No. 4,111,447 A, U.S. Pat. No. 7,367,576 B2.
The inventor is only acquainted with three bicycles that can be used by adults and that have a very small folding size: U.S. Pat. No. 4,598,923 A, U.S. Pat. No. 6,595,539 B1 and U.S. Pat. No. 7,306,249 B2.
Regarding U.S. Pat. No. 4,598,923 A: The essential disadvantage of this bicycle is that the folding depth with the two wheels arranged next to each other and the box enclosing these wheels would lead to such a box depth that a comfortable ride is no longer possible. The disadvantages of this design-related large horizontal distance between the rear-wheel axle and the cyclist's center of gravity have already been pointed out above. Due to the design-related large front center the cyclist has to stretch his arms comparatively far to the front while the steering-tube head with the head tube and the front-wheel axle are on a line. The bicycle therefore lacks suitable means for controlling the wobbling front wheel during a fast ride. In addition, the bicycle achieves only low meters of development, because only a single-speed chain drive is provided for the small wheels.
Regarding U.S. Pat. No. 6,595,539 B1: In addition to the disadvantages mentioned above, it is disadvantageous that the bicycle does not provide any conventional cranks or that the low folding size cannot be achieved, when cranks are used, and that due to many frame parts and hinge connections a stable construction of the bicycle would result in a high bicycle weight and/or the riding stability is not ensured. A construction having larger wheels would lead to a larger folding size.
Regarding U.S. Pat. No. 7,306,249 B2: The folding size is approximately 58×33×25 cm. In addition to the disadvantages already mentioned for this bicycle, the further disadvantage consists in that the chainstay length for larger wheels is large due to the design, because in the folded state the front wheel is arranged between the rear wheel and the bottom bracket. Thus, the folding size mentioned can only be achieved with 8-inch wheels. 10-inch wheels, for example, would already require a folding length of approximately L=68 cm. For accommodating the front wheel between the bottom bracket and the rear wheel in the folded state and for arranging the chain run, fragile chainstays are designed, allowing reasonable doubts concerning the required strength of the chainstays in practical use. It is a further disadvantage that the front center of the bicycle has the same length as the chainstay and that the head angle is less than 10°. The result is that the front wheel cannot be braked according to standard with a braking deceleration of 3.4 m/s2 without the rear wheel lifting off the ground. In addition, the riding stability and the cycling characteristics are compromised for the reasons already mentioned. However, due to the design it is not possible to increase the front center, required for improvement, since otherwise it would no longer be possible to fold the steering column, as is provided here, parallel to the longest side of the folding size. An increase of the head angle is also only possible to a limited extend because when the head angle is increased without the possibility of any appreciable increase of the front center, the handlebar is displaced toward the rear and riding while standing up is made impossible.
Except for these bicycles mentioned all folding bicycles known by the inventor for comfortable use by adults have the disadvantage, that the sum of the two longer edges of the folding size amounts to more than 100 cm. Furthermore, the lightest conventional folding bicycles weigh at least 6.5 kg, however only while accepting particularly small wheels of 10 inch and less. Conventional bicycles having larger wheels weigh at least almost 10 kg.
In the majority of bicycles designed for riding while sitting, the distance between the handlebar and the cyclist's torso is design-related relatively large. When riding while sitting, the cyclist's back is not upright, so the cyclist has to move his head backward and has to tension his back and the neck muscles. Thus he expends additional energy that he cannot use for riding. The back/shoulder and neck areas are always strained. It is a further disadvantage that the cyclist, while riding standing-up, has to bend forward and with a bent body cannot utilize his entire weight for propulsion. An example are in U.S. Pat. No. 4,598,923.
The compact bicycles disclosed in DE 40 06 095 A1, DD 2 84 200 A5, U.S. Pat. No. 4,389,055 A exhibit the disadvantage that the front wheel is driven, whereby the bicycle has to be ridden in a seated position and the cyclist's weight increases the grip between the driven wheel and the ground only to a small fraction, hence frequent slip of the driven wheel is to be expected for greater accelerations.
In the bicycle disclosed in DE 195 21 064 A1, the bottom bracket is arranged, seen in travel direction, in front of the front wheel hence the bicycle cannot be ridden while standing-up.
Furthermore bicycles are known where in particular a transversal seat tube and/or a top tube are absolutely required due to the design. This has the disadvantage that the bicycle is not well suited for riding while standing-up, because the required legroom is missing. In addition, it is more difficult to design constructions having a top tube to be foldable. Examples for bicycles designed having a top tube due to their design and/or with a transversal seat tube: EP 1 600 368 A2, U.S. Pat. No. 5,186,482 A, WO 2010/054 500 A1, DE 32 25 340 A1, DE 198 03 462 A1, U.S. Pat. No. 4,895,386 A, DE 603 03 842 T2.
In the bicycle from U.S. Pat. No. 1,381,281 A the effect described above, that the front wheel lifts off during stronger accelerations, does not arise despite the cyclist being seated while riding. However the disadvantage is, that the bicycle cannot be ridden comfortably while seated, because the pressure point onto the pedals, seen horizontally, is very close to the cyclist's center. Due to the design, the bicycle cannot be ridden while standing up and is also not intended for this purpose. The embodiment provided for women (FIG. 1 from U.S. Pat. No. 1,381,281 A) cannot be ridden while standing up, because under the saddle the handlebar is connected to the connecting tube to the fork stem and the required legroom for cycling while standing up does not exist. The embodiment provided for men (FIG. 3 from U.S. Pat. No. 1,381,281 A) cannot be ridden while standing up, because the handlebar stem below the saddle runs very flat toward the front and thereby does not achieve enough height for the legs to pass under the handlebar when cycling while standing up. In this embodiment also the handlebar grips are arranged lower than the seat surface so that the cyclist could not reach around the handle grips when cycling upright. In the embodiment provided for men, there exists the additional disadvantage that during stronger deceleration the cyclist would fall forward over or against the handlebar. In all embodiments there exists the disadvantage that during stronger deceleration, the cyclist cannot support his own inertia and would fall forward. In both embodiments, the saddle, arranged in a vertical line above the bottom bracket, impedes cycling while standing up. Further disadvantages consist in that the frame cannot be folded together, that the frame is not designed as a single-beam type, that the preferred embodiment only achieves a development of approximately 3.8 m/crank revolution (estimated construction of the preferred embodiment: 8-inch wheels having a driving sprocket with 54 teeth and an output sprocket having 9 teeth) and that a single-speed chain drive having a very large driving sprocket and an output sprocket arranged between the frame and the rear wheel is provided, thereby the frame has to be guided from inside to outside between the driving sprocket and the output sprocket and thereby the chainstay length cannot undershoot an ascertainable minimum.
In many of the bicycles already mentioned and otherwise known, the use of a single-speed chain drive and small wheels, result in very low meters of development, not suitable for normal speed. Because these bicycles are not suitable for daily use, a detailed description of extending disadvantages beyond the above mentioned disadvantages is omitted here. Examples are in: US 2007/0,069,499 A1, U.S. Pat. No. 4,895,386 A, GB 2 373 771 A, US 2004/0,180,758 A1, DE 43 16 366 A1, DE 201 12 963 U1, US 2007/0,024,023 A1, US 2005/0,230,933 A1, U.S. Pat. No. 6,595,536 B1, U.S. Pat. No. 4,598,923 A.
Bicycles are furthermore known, where the bottom-bracket axle and the rear-wheel axle coincide and the rear wheel is driven directly or via an intermediate gear box. The disadvantage of these bicycles consists in the fact, that the transmission ratios achievable for the bicycle drive are very small and thus require large wheels to achieve a suitable transmission, whereby no compact folding size can be achieved. At least 20-inch wheels are requisite so that the pedals obtain the necessary ground clearance. In addition, no conventional bottom brackets and cranks can be used. Examples are in: WO 98/00 331 A1, EP 0 010 201 A1, FR 411 607 A, FR 2 366 491 A1, FR 876 657 A, DE 138 824 A, FR 493 509 A, WO 2007/057 992 A1.
In WO 2009/056 078 A2 a two-chain drive drives the rear wheel and the bottom-bracket axle and the rear-wheel axle coincide. Hence the driving sprocket of the first transmission shaft is connected to the same shaft on which the output sprocket of the second transmission shaft is mounted. The driving sprocket of the first transmission step is connected conventionally to the crank. To achieve an appropriate chainline distance of the first transmission step despite the two-chain drive, the chainline distance of the second transmission step relative to the central reference plane of the bicycle is to be designed approximately so small that it corresponds to half the width of the rear-wheel tire. The disadvantage of this drive system is therefore that 26-inch wheels have to be used so that rim and tire of the wheel do not collide with the second transmission step, this likewise, due to the design, not achieving a compact folding size. A further disadvantage consists in that no commercial bottom brackets can be used because the bottom bracket also supports the rear wheel.
In all known bicycles that are ridden standing up the cyclist supports himself only on two points at the bicycle, to be precise with the feet on the pedals and with the hands on the handlebar. If small front wheels are used, in accordance with the explanations above, particularly during fast cycling and/or while cycling over obstacles, the directional stability is severely impeded. In all known bicycles that are ridden while standing up, there is in addition the disadvantage that during stronger braking the cyclist is moved forward due to his own inertia and at first experiences an uncontrolled relative motion in the direction toward the handlebar, the cycling stability being compromised in the process. Finally there is the disadvantage the shoulder and back muscles of the cyclist are tensioned by the arms pointing forward and the cyclist at the same time tending to slightly lean forward while cycling. Examples are in: JP 2010 260 457 A, FR 2 876 657 A1, EP 1 995 165 A2, WO 2006/111 590 A1, KR 10 0 768 964 B1, US 2004/0,004,341 A1, the bicycles microslider and dreamslide by dreamslide, S.A, Bures-sur-Yvette, France, and the bicycles MCS16″ and MCS across the city by Maderna Cycle Systems, Vienna, Austria. The foot loops used in FR 2 876 657 A1 and the pedals that are bent upwards from the tip of the foot alleviating the disadvantages, that have been mentioned, only slightly in that the feet can support the cyclist's inertia during stronger deceleration likewise against the bent-off pedals.
Above what has been mentioned, it is a disadvantage of the vehicle from US 2004/0,004,341 A1 that the transmission ratios realized by the single-speed chain or gear drive, for small wheels do not enable appropriate development. Due to the arrangement of a base between the bottom bracket and the front wheel, the cyclist must cycle bent forward and/or with arms stretched forward. The small distance between the bottom bracket and the rear-wheel tire is achieved in the vehicle only because the bottom bracket is fastened to the frame by a separate arm pointing upward and because therefore all transmission parts (sprockets and chain or gear wheels) are arranged above the supporting frame.
In addition, the bicycles MCS16″ and MCS across the city by Maderna Cycle Systems, Vienna, Austria, exhibit the following disadvantages: The bicycle is only suitable for persons with small difference in terms of body height because the height of the steering tube that is connected to the fork stem cannot be height-adjusted. Furthermore at its upper end the steering tube exhibits a front-facing handlebar stem that is connected to the handlebar and that positions the handlebar further away from the cyclist to the front. The steering and braking concept of these bicycles therefore evidently provides that while braking, the cyclist braces his weight against the handlebar by stretching the arms and thus maintains his position relative to the bicycle when braking, with the disadvantages mentioned above. The folding concept of the bicycle therefore provides a hinge having an axis of rotation parallel to the rear-wheel axis, so that the unit consisting of front wheel, front-wheel fork, head tube, and handlebar, is folded scissors-like with the rear frame part, with the disadvantages, mentioned above, of the very long folding dimension.
The cycling/steering and braking concepts of the bicycles microslider and dreamslide by Dreamslide S.A. Bures-sur-Yvette, France, due to the arrangement of the handle grips inclined to the front and the position of the handlebar relative to the body of the cyclist (handlebar position slightly lower than the center of the cyclist, handlebar position so far in front of the cyclist's torso, that out-of-saddle riding is possible) evidently also provide for the cyclist to brace his weight against the handlebar by stretching the arms while braking and thus maintains his position relative to the bicycle with the disadvantages that have been mentioned. It is also a disadvantage of these bicycles that only the handlebar can be folded in.
All bicycles having particularly small wheels exhibit the disadvantage that the driving wheels when running onto an insurmountable obstacle are inevitably pushed away to one side whereby also the cyclist falls uncontrollably to one side.
The disadvantage of using commercially available cranks having a crank length of at least 165 mm for cycling while standing up are described in detail in US 2008/0,217,881 A1. Here also the disadvantages of US 2002/0,163,159 A1 and US 2003/0,030,245 A1 are discussed in detail. However, the disadvantage of the embodiment known from US 2008/0,217,881 A1 for a crank to be ridden while standing up consists in that no commercially available bottom brackets and driving sprockets can be used here because the bottom bracket has to be supported between the driving sprocket and the cranks relative to the bicycle frame, that rather the bottom bracket and the cranks are expensive special components, that the chain drive is arranged inside the frame and thus more difficult to access for maintenance, thereby the manufacturing costs for the bicycle frame are correspondingly high, that the foldability of the frame can be made possible only at considerable effort and that, as already described above for the correspondingly designed bicycle by dreamslide, due to the design there result chainstay lengths of more than 25 cm (see also the bicycle dreamslide by dreamslide S.A, Bures-sur-Yvette, France).
In the bicycle microslider by dreamslide S.A, Bures-sur-Yvette, France, a two-chain transmission is used to achieve suitable transmissions and to achieve good ground grip of the rear wheel despite the small wheels. In order to arrange the two-chain transmission with an appropriate width and a small axial pedal distance, the chain transmission has to be arranged inside the bicycle frame of two-part design between the rear wheel and the bottom bracket. Due to the required arrangement of the output wheel of the first transmission step, there results a design-related great chainstay length with the disadvantages described above in terms of the cycling stability and the achievable folding size.
An elliptically designed driving sprocket is provided for the bicycle presented in FR 2 876 657 A1, to reduce the rate of fall of the cyclist onto the pedals. Here too, it is disadvantageous that no conventional cranks can be used and that the bicycle cannot be folded together.
The bicycle disclosed in KR 10 0 768 964 B1 exhibits the disadvantage that each pedal is rotatably connected to the bicycle also at the level of the rear-wheel axle. Therefore a corresponding rear-wheel axle and a supporting bicycle frame have to be designed on both sides.
In addition to the disadvantages already mentioned, the bicycle in EP 1 995 165 A2 exhibits the disadvantage that it is very expensive to manufacture due to the complex frame structure.
The bicycle to be ridden while standing up, disclosed in WO 2006/111 590 A1, exhibits, seen horizontally, a chainstay length of at least 21 cm if, as is shown, an 8-inch wheel is used. The chainstay length would amount to at least 22.5 cm when using a 9-inch wheel. Due to the handlebar stem pointing forward, the handlebar is positioned so far in front of the cyclist, seen in the cycling direction, that the cyclist must stretch his arms sufficiently, with the disadvantages mentioned. There is also the disadvantage that the design does not provide means for handling the wobble of the small 8-inch wheel resulting from road bumps and cycling activity. It is also problematic to run over obstacles due to the small wheels and the lack of control of the front wheel. Due to the single-speed chain drive and the small 8-inch wheels results only a development of approximately 54/9*8 inch*π=3.83 m/U for the bicycle.
Due to the design the chainstay length of approximately 21 cm is only achieved in that the supporting frame part running in the central reference plane extends above the 8-inch rear wheel and exhibits at the rear wheel two ends that are connected to the supporting frame part above the tight side of the chain and must extend downward from the frame so as to arrange the rear wheel and the output sprocket of the chain drive inside the ends of the rear wheel.
A disadvantage of this arrangement is that the supporting frame part is arranged above the two wheels so that due to the construction suitable bottom-bracket heights of the bottom bracket arranged directly below the supporting frame part can only be achieved for wheel sizes up to a maximum of 10 inch. For larger wheels the bottom bracket would have to be arranged in an X-frame further below the horizontal frame carrier.
Due to the design, there is further the disadvantage that an unconventional rear-wheel brake has to be provided that in the present case is operated by a pedal, the pivot of the pedal having to be arranged between the rear wheel and the bottom bracket with the consequence that, measured horizontally, more than 10 cm is required between the bottom-bracket axle and the outer circumference of the rear wheel so that the brake construction can be arranged. The chainstay length of approximately 21 cm is thus only realized for 8-inch wheels due to the design. In a design of the bicycle having 10-inch wheels, a chainstay length of more than 25 cm would result.
Due to the arrangement and guidance of the handlebar and of the chainstay length of 21 cm achievable for an 8-inch wheel, the illustrated wheel base of approximately 72 cm results in a weight distribution of the cyclist of at most 71% on the rear wheel and at least 29% on the front wheel.
For example for a 100 kg cyclist due to the design the following force ratios between the rear wheel and the ground result: Since the cyclist rides while standing up, he puts his entire weight on the pedals. This exerts a torque of approximately 100×9.81×130×8 inch×pi/3,830=21,250 Nm onto an 8-inch rear wheel in the case of the mentioned development of 3.8 m/crank revolution and a crank length of at least 130 mm. This means, a tangential force of 21,250/8 inch*2=209 N acts between the rear wheel and the ground. At this moment, the pedals are at the foremost point, i.e. 210 mm+130 mm=340 mm from the rear-wheel axle. Thus a weight force of 100×9.81×(1−340/720)=518 N rests on the rear wheel considering the wheel base of 720 mm. To achieve sufficient friction of the rear wheel to the ground, the friction coefficient between the rear wheel and the ground thus has to amount to at least 0.4 to prevent the rear wheel from slipping on the ground. In addition, it is very unfavorable if not even impossible to use pneumatic tires due to the smaller wheels. Taken together the bicycle is suitable only to a limited extent for cycling on wet and/or less firm grounds like soil or gravel.
The frame consists of a front and a rear frame part that can be telescoped one inside the other to achieve a favorable packed size and due to the design are therefore constructed in a straight line. Due to the design, the bottom bracket therefore has to be arranged below the rear frame part to enable on the one hand the frame parts to be telescoped into each other and on the other hand to be able to guide the tight side of the chain below the ends of the rear wheel. Because the steering head that is connected to the front frame part, for achieving the desired favorable packed size, is arranged directly above the front wheel and thus the handlebar can be removed directly above the steering head or folded together, there is the construction-related disadvantage that the design shown with an 8-inch wheel can achieve only a bottom-bracket height of approximately 22 cm. In a design having a 9-inch wheel, correspondingly only a bottom-bracket height of 24 cm can be achieved. There is also the disadvantage that bending moments act between the front and the rear frame parts therefore a minimum insertion length is required that covers both frame parts.
Finally, the intended head angle is not inside the standard 65-75°. This has the disadvantage of a more inferior steerablility of the bicycle.
In all bicycles with chain transmissions that can be ridden while standing up and/or that exhibit small wheels of less than 20 inch, there exists the further disadvantage that the output sprocket of the chain transmission is arranged between the bicycle frame and the rear wheel, a possible chain guard that supports the rear wheel also counting as part of the bicycle frame.
This arrangement exhibits the construction-related disadvantages,
that in the case of a single-speed chain drive, the output sprocket has to exhibit at least 9 teeth, hence to achieve an appropriate development for 12-inch wheels a driving sprocket should have at least 52 teeth.
that a minimum width of the rear-wheel axle suspension of at least 120 mm is requisite due to the frame lying outside at the rear wheel and due to the fastening screws of the rear-wheel axle,
that with a single-speed chain transmission and an outside driving sprocket the chainstays have to form a curve from the bottom bracket to the rear-wheel axle, therefore relatively large pedal distances and corresponding chainstay lengths are required to get a sufficient distance between the crank and the bicycle frame or the rear-wheel axle or the fastening screw for the rear wheel.
Examples for this embodiment can again be found in the bicycles MCS 16″ and MCS across the city by Maderna Cycle Systems, Vienna, Austria, where the chainstay length is more than 23 cm.
DE 152 616 A describes a compact foldable bicycle that exhibits the following disadvantages:
Due to the construction, the pedals are not connected to a crank, but rotatably to the crank shaft that is eccentric at its ends and the eccentricity between the crank shaft and the pedal axle amount to only a few centimeters. The effort of the cyclist leads only to a very small driving torque, thus no suitable accelerations can be achieved with the bicycle.
Due to the construction, the front wheel is approximately only half the size as the rear wheel so that the targeted small packed size can be achieved. If a larger front wheel were to be used, it would no longer be possible to realize the inventive idea of the bicycle. To achieve the targeted packed size, due to the construction the crank shaft is approximately at the same height as the rear-wheel axle. To implement the targeted bicycle geometry in connection with the required bottom-bracket heights, due to the construction a 16-inch wheel is to be used as rear wheel. Independent of the wheel size there is the design-related disadvantage that appropriate crank lengths cannot be achieved due to the bicycle geometry in connection with the required ground clearance of the pedals.
A chainwheel is used that is positioned on the inside, whereby usual cranks can no longer be used.
To achieve the smaller packed size the angle of the head tube has to amount to more than 85°. Therefore the front wheel cannot be decelerated according to the standard with a braking deceleration of at least 3.4 m/s2 without the rear wheel lifting off the ground.
To fold the bicycle, front wheel, handlebar and head tube have to be disassembled.
A gear box is positioned inside the frame. To achieve unimpeded meshing of the gear box, the frame construction must have the corresponding stiffness.
The bicycle is provided with a frame that due to the construction exhibits a side panel each on both sides of rear wheel respectively front wheel and thus is of at least two-part design between the ends of the rear wheel and the bottom-bracket housing and between the bottom-bracket housing and the front-wheel suspension.
The largest packed size of the folded bicycle amounts to at least 65 cm.
Essential aspects of the prior art described above are again pointed out below:
a. All known bicycles that are ridden while standing up exhibit, seen in the travelling direction, a handlebar stem and/or handles that point forward plus a horizontal part of the distance between the bottom-bracket axle and the steering-tube head of more than 300 mm. With the steering and braking concept of the bicycles the cyclist braces himself against the handlebar with his arms that are stretched if possible, so he maintains his position relative to the bicycle, with the mentioned disadvantages concerning the cycling stability and safety.b. All known bicycles having wheels of at most 16 inch have a bicycle drive with a chain transmission having an output sprocket arranged, seen axially, between the bicycle frame and the rear wheel, or having an output sprocket, seen axially, on the side of the rear wheel opposite the bicycle frame, a possible chain guard that supports the rear wheel also counting as part of the bicycle frame, with the mentioned disadvantages concerning the width of the chainstay and/or the requisite chainstay length.c. All known feasible bicycles that use cranks for riding, exhibit folding concepts that only achieve a folding size of more than H+W+D=115 cm. The sum of the two longest folded sides of all known bicycles amounts to more than 100 cm. The longest folding-size length of all known bicycles amounts to more than 55 cm.d. All known bicycles exhibit the disadvantage that they don't achieve appropriate development of at least 4.5 m per crank revolution and no suitable velocity with acceptable pedaling frequency, or they achieve this development, but exhibit a chainstay length of more than 23 cm.e. For all bicycles having an average wheel size of at most 380 mm and a bicycle drive with a driving wheel, arranged outside the bicycle frame, the friction coefficient of the friction pairing rear wheel/ground has to amount to at least 0.4, so that the rear wheel does not slip on the ground when accelerating while standing up. This in principle entails the risk of slipping on soil and/or wet ground.